Greeting cards are typically printed with static designs and in large quantities. They can commonly be purchased at card stores such as Hallmark, bookstores and other retail locations. After a user purchases the greeting cards, she can handwrite personalized information on the greeting cards and mail them to family members, friends, or business clients. Card printing vending machines have been developed to allow the card purchasers to select the card designs and input their own personalized messages before the actual cards are printed.
In recent years, online photo services such as Shutterflys, Inc., based at Redwood City, Calif., have established services for users to upload, store and share their digital photo images. The users can order physical photo products such as photographic prints, photo books, CD's, etc. The print orders are fulfilled using automated digital printers, and shipped to the recipients as specified by the user. As the photo products are continuous produced, the products need to be separated in batches so that the correct group of products can be shipped to the intended recipients.
U.S. Pat. No. 4,124,290 disclosed a system for interfacing an automatic processing machine with a stack of documents. In the disclosed system, “a stack of documents is transported one-at-a-time, under control of an automatic machine. A machine-readable card is inserted between preselected documents in the stack. When the transport detects a passage of the card through the transport system, the machine is commanded to perform a specific function. The exemplary machine described herein is a microfilm camera and the illustrative functions are two side copying and batch or file marking.” The approach of using machine-readable card is disadvantageous, however, because it adds cost and complexity to the system.